The present invention relates to a motor vehicle, especially a truck, with a cab and with a cooling system for an internal combustion engine, said cooling system comprising a heat exchanger located in an engine compartment and provided with an associated blower, and one or more additional heat exchangers located outside the engine compartment, and with an additional blower associated with said additional heat exchangers.
It is now required that the noise produced by motor vehicles, especially trucks, be reduced by approximately 10 dB(A) by comparison with the values presently allowed. This means that the noise produced by the cooling system, especially the fan, must be reduced by at least the same amount. Numerous proposals have been made to achieve this. Considering only the construction cost of the cooling device, the simplest solution is to use a low-noise radial fan in conjunction with a heat exchanger mounted in the usual fasion, a so-called front radiator (German Offenlegungsschrift No. 2,530,742).
A radial fan, however, requires a much greater installation depth than the axial fan usually employed, resulting in installation problems. Since the total length of the vehicle may not be increased, mounting the radial fan in many cases shortens the truck bed by at least the amount by which the installation depth of the radial fan is greater than that of an axial fan.
It is also known (German Offenlengungsschrift No. 2,530,741 and German Offenlegungsschrift No. 2,530,743) to mount the entire cooling system behind the cab, but this results in the same problems relating to shortening of the truck bed.
It is also known (German Offenlegungsschrift No. 2,747,785) to mount the cooling system on the cab roof. It is true that this avoids the above-mentioned disadvantages relating to space requirements, but there are considerable objections to an arrangement of this kind because there is a danger that, especially in accidents, coolant could escape from the heat exchanger and pose the danger of scalding the occupants of the cab.
It is also known to mount two cooling systems side by side in the engine compartment and to operate their corresponding axial blowers at a reduced rpm, whereby noise reduction is achieved. However, in many cases, such a design cannot be used, or can be used only with difficulty, because of limited space.
Use of a main cooling system and one or more additional cooling systems is also the subject of the present invention.
More specifically, an object of the present invention is to provide a motor vehicle such as a truck with a cooling system whose noise, on the one hand, is reduced but which can, on the other hand, be installed without losing truck bed space and which poses no danger of scalding from escaping coolant.
This and other objects of the present invention are attained by providing a motor vehicle with a cab and a cooling system for an internal combustion engine, said system comprising a heat exchanger disposed in an engine compartment and provided with an associated blower and at least one additional heat exchanger located outside the engine compartment and with which an additional blower is associated, and wherein said additional blower is mounted on a roof of the cab and is connected through channel means with said additional heat exchanger which is located within said channel means in the vicinity of one wall of the cab and at a level below the roof of the cab when the vehicle is in an upright position.
In a disclosed embodiment of the present invention the channel means includes a channel in the vicinity of one wall of the cab and within which the additional heat exchanger is located and a connecting channel between said channel and the additional blower mounted on the roof of the cab.
This arrangement provides sufficient space for mounting a blower which is suitable in terms of the noise it produces, so that the ambient noise produced by the additional system and the interior noise level may be kept low. Of course, optimally designed blowers may be used, for example radial blowers with spiral cases, axial blowers with guide vanes behind the axial impeller or cross-flow blowers with a high pressure-coefficient and a correspondingly low circumferential velocity. If necessary, these blowers can also be used in conjunction with a narrow diffuser, resulting in a low-loss conversion of dynamic to static pressure. The channel which holds the additional heat exchanger or exchangers can be made breakage-resistant by simple means, so that the danger of a defect in the heat exchanger resulting from an accident can be sharply reduced. In addition, the escaping coolant is guided in the channel so that there is a very small danger of the hot coolant being able to penetrate the cab in the event of a defect or an accident.
Another embodiment of the invention provides for the channel containing the additional heat exchanger or exchangers being mounted laterally with respect to the cab. A free space, permitting easy installation of a channel with a heat exchanger, is located in this area in cabs that are slightly narrower than the body of the truck. It may be advantageous in this connection for the channel to be intergrated together with the additional heat exchanger or exchangers in the side wall of the cab. Such an arrangement is advantageous, on the one hand, in cabs whose width matches the width of the truck body behind, and also the visual appearance of the truck is not affected in a disadvantageous manner by the channel and the additional heat exchanger.
In another embodiment of the invention, the channel with the additional heat exchanger or exchangers is located in the vicinity of the rear wall of the cab, preferably between the seats. Such an arrangement, on the one hand, does not have a disadvantageous effect upon the truck's appearance, and, on the other hand, the heat exchanger is further protected against damage as the result of an accident. It is advantageous in this connection not to increase the structural dimensions when the channel containing the additional heat exchanger or exchangers is integrated into the rear wall of the cab. This can be accomplished, in particular, in the area between the seats located in the cab.
In order not to increase excessively the weight of the cab, which could be disadvantageous in the case of a cab which is tiltable about the area of its leading edge, in another embodiment of the invention provision can be made for locating the channel with the additional heat exchanger or exchangers on the body of the vehicle, and connecting it to a connecting duct mounted on the cab by means of, preferably, separable connections. Such an arrangement of the channel is feasible both in the lateral area of the cab and also in the vicinity of the rear wall. It is advantageous in this connection for the cab to have a depression in the vicinity of the channel with the additional heat exchanger or exchangers. On the one hand, this ensures that there will be no need to take into account any increase in the structural length or reduction of truck bed area, while, on the other hand, tiltability of the cab remains ensured.
In another embodiment of the invention, provision is made for at least partially lining the connecting channel from the blower to the additional heat exchanger or exchangers with noise-damping and preferably absorbent material. This further reduces the noise generated by this subassembly of the cooling system. Moreover, this has the advantage, when the material is absorbent, that the coolant which escapes in the event of a defect will be absorbed at least partially by this material.
In another embodiment of the invention, it is provided that a sealing means or element in the form of a valve is located between the additional heat exchanger or exchangers and the blower, preferably in the connecting channel, which closes off the channel. This sealing means or element, preferably controlled by position sensors, shuts off the connection to the blower in the event of an excessive tilting of the vehicle either sideways or lengthwise, indicating an accident, so that the danger of escaping fluid entering the cab area is further reduced.
In order to achieve uniform flow to the additional heat exchanger or exchangers, it is advantageous to locate air-guiding elements in the channel upstream of the heat exchanger or exchangers.
In order to decrease further the amount of noise which escapes to the exterior, another embodiment of the invention provides for locating a noise damper upstream of the additional blower.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, several embodiments in accordance with the present invention.